Effects of Laparoscopic Sleeve Gastrectomy and Roux-En-Y Gastric Bypass on the Improvement of Sleep Quality, Daytime Sleepiness, and Obstructive Sleep Apnea in a Six-Month Follow-up

Background: The number of bariatric surgeries has increased in recent years, and major attempts have been made to find the best surgical procedure. Laparoscopic sleeve gastrectomy (LSG) and Roux-en-Y gastric bypass (RYGB) are the most common bariatric surgery procedures. This study aimed to investigate the effects of these two procedures on improving sleep quality, daytime sleepiness, and obstructive sleep apnea. Materials and Methods: This case-control study was performed on two groups of patients (n=60 per group). The case group included obese candidates for LSG or RYGB, and the control group consisted of obese patients without any surgical interventions. The sleep quality, obstructive sleep apnea (OSA) risk, and daytime sleepiness were examined, using the Pittsburgh Sleep Quality Index (PSQI), Stop-Bang questionnaire, and Epworth Sleepiness Scale (ESS), respectively. The results were recorded before and six months after the intervention and compared between the two groups. Results: There was no significant difference in the mean scores of ESS, PSQI, and Stop-Bang questionnaire between the two groups before the intervention (P>0.05). However, the mean scores of PSQI and its dimensions, ESS, and Stop-Bang questionnaire significantly improved in patients undergoing surgery (P<0.05). The results of linear regression analysis also showed significant improvements in the ESS, PQSI and Stop-Bang scores in the intervention group. Body mass index (BMI) reduction improved the scores of PSQI, ESS, and Stop-Bang questionnaire in patients, with impact factors of 0.032, 0.700, and 0.025, respectively (P<0.05). Conclusion: LSG and RYGB surgeries significantly improved the patients’ sleep quality, decreased daytime sleepiness, and reduced the risk of OSA. Overall, BMI reduction and lack of OSA can significantly affect sleep quality.

episodes of upper airway obstruction, resulting in apnea and hypopnea during sleep (4). The exact mechanism of the association between OSA and obesity is not wellestablished yet, but it may involve fat deposition in the upper airway, leading to obstruction (5). The relationship between OSA and obesity may be attributed to fat accumulation in the upper thoracic region and neck, which can cause upper airway narrowing (6).
Approximately 3-7% of the general population may be affected by OSA (7). According to previous studies, the prevalence of OSA is estimated at 32.9%. In obese men with a body mass index (BMI) >40 kg/m 2 , the prevalence of this disorder reaches up to 64% (8). Also, the prevalence of OSA is 42-48% in obese men and 8-38% in women with BMI >40 kg/m 2 (9). Another study found that the prevalence of OSA in obese candidates for bariatric surgery was nearly 64% (10). Reports show that the prevalence of OSA in obese people with BMI >35 kg/m 2 ranges from 60% to 83% (11). Also, many studies have shown that OSA itself can increase the risk of obesity (12).  (20). Several studies have shown that patients experience a 50% to 70% reduction in overweight after RYGB. Also, improvement of insulin resistance, dietary habits, and cognitive function has been reported after gastric bypass (21,22). However, there is not enough evidence to support the improvement of sleep apnea, daytime sleepiness, and sleep quality following rapid weight loss (19). Therefore, considering the increasing prevalence of obesity and its impact on sleep, besides the increasing demands for bariatric surgery, we aimed to investigate the effects of LSG and RYGB on the improvement of sleep quality, daytime sleepiness, and OSA at six months after surgery.

MATERIALS AND METHODS
This case-control study was conducted on 120 obese patients, referred to Alzahra Hospital in Isfahan, Iran, during 2017-2018. Sixty patients who were candidates for either LSG or RYGB were assigned to the intervention group, and 60 obese patients, without any surgical interventions, were assigned to the control group.
The inclusion criteria were as follows: 1) age over 18 years; 2) body mass index (BMI) >35 kg/m 2 ; 3) being a candidate for either LSG or RYGB; and 4) giving a written informed consent to participate in the study. On the other hand, patients were excluded from the study if they met any of the following criteria: 1) history of pulmonary diseases, such as asthma and chronic obstructive pulmonary disease (COPD); 2) history of either RYGB or LSG in the control group; 3) unwillingness to continue participation in the study; and 4) non-attendance of the six-month follow-up. Two patients were excluded from the study due to non-attendance of the follow-up.  The collected data were entered in SPSS version 22.
Mean±standard deviation and frequency (%) were measured to represent the data. Fisher's exact test was used to compare qualitative variables between the groups.
Independent samples t-test was also applied to compare the means of quantitative variables between the groups. Paired t-test was performed to compare the means of quantitative variables before and after the intervention.
Moreover, Wilcoxon signed-rank test was used to compare the mean scores of PSQI before and after the intervention.
Also, linear regression analysis was performed to determine factors affecting changes in the scores of Stop-Bang questionnaire, PSQI, and ESS. P-value less than 0.05 was considered statistically significant.  Bang score ≥4). Therefore, in a high proportion of patients, sleep quality, daytime sleepiness, and reduction of OSA risk improved.  In contrast, none of these factors had significant effects on the reduction of OSA risk (P>0.05) ( Table 4).   Finally, sleep quality may be affected by not only the used medications, but also by stomach inflammation, hyperplasia, physical activity, gastroesophageal reflux disease, and several other comorbidities (47)(48)(49). Although these disorders and confounding factors were not considered in this study, age and sex were matched, and the presence of OSA, tobacco use, and type of bariatric surgery were adjusted as confounding factors; this can be considered a major strength of this study. Also, another strength of this study was the use of linguistically and structurally valid questionnaires. However, further studies with a larger sample size are needed on bariatric surgery, and more attention must be paid to comorbidities that may be associated with sleep disorders and obesity.

CONCLUSION
The results of the current study showed that bariatric surgeries, such as LSG and RYGB, led to significant weight loss and BMI reduction. Also, LSG and RYGB may play significant roles in the improvement of sleep quality and reduction of daytime sleepiness and risk of OSA. Also, BMI reduction and absence of OSA-associated comorbidities can have significant effects on the sleep quality of these patients. Therefore, in obese patients suffering from OSA, these surgeries can be effective in improving the quality of sleep, daytime sleepiness, and quality of life in general.